'Vikings' season 4 episode 20 spoilers: Victory and tragedy collide in explosive season finale; new character to appear in aftermath

Ragnar's sons are truly unstoppable as the Great Army's vengeful conquest continues in the upcoming final episode of "Vikings" season 4. Now that Ivar (Alex Høgh) has proven his mettle as a battlefield tactician, one can't help but wonder what other tricks the crippled mad genius has up his sleeves.

In an interview with Entertainment Weekly, series creator Michael Hirst shared that Ivar, compensating for his crippled state with brilliant brain power, can approach warfare in innovative ways.

"He's appreciated that the scale has gone up now. The armies are bigger, the possibilities are bigger," Hirst said, further teasing viewers to watch out for more varied approaches to warfare that go beyond the usual shield wall.

On a more personal note, however, Ivar is rumored to have a confrontation with one of his brothers that may lead to some inevitably deadly consequences. This purported outcome came from early leaks of the upcoming episode made through the Russian media. The episode has since been removed, but some Russian-speaking fans of the show have already watched it and shared some significant details online.

The spoilers floating around seem to confirm what Hirst has earlier teased about important characters meeting their end in the "Vikings" season 4 finale. Tragedy does not only come for the Lothbrok brood, but for Floki (Gustaf SkarsgÃ¥rd) and Helga (Maude Hirst) as well when the terrified Spanish girl Tanaruz (Sinead Gormally) finally decides to take matters into her own hands.

"There doesn't seem to be any way of avoiding it," Hirst said when talking about Floki and Helga's side of the story in the aforementioned interview with Entertainment Weekly. "There's a tragedy waiting to happen."

While it goes without saying that the Great Army will indeed succeed in their quest to avenge Ragnar's (Travis Fimmel) death, a new face will arise in the aftermath of the chaos and pose a real threat to Ivar's battle planning genius.

Actor John Rhys Myers is set to appear in the upcoming finale episode as a warrior bishop named Heahmund. While this season 4 appearance will only serve as an introduction to his character, Hirst teased that Heahmund will play a much larger role in the subsequent season 5.

"He's a man of Wessex, and he's gonna come in as a worthy opponent to Ivar," Hirst said.

The finale episode of "Vikings" season 4 airs on Wednesday, Feb. 1, at 9 p.m. EST on HISTORY.